From 790034e9ef3c082a8c2cb674c687c7fa205f695d Mon Sep 17 00:00:00 2001
From: Stephan Hageboeck <stephan.hageboeck@cern.ch>
Date: Tue, 11 Mar 2025 16:34:59 +0100
Subject: [PATCH 1/2] [Post-install] Add a simple post-install test.

To test that ROOT is usable after it has been installed, a small CMake
project is added that checks the outputs of hsimple.
---
 test/PostInstall/CMakeLists.txt  | 21 +++++++++++++++++++++
 test/PostInstall/readHSimple.cxx | 19 +++++++++++++++++++
 2 files changed, 40 insertions(+)
 create mode 100644 test/PostInstall/CMakeLists.txt
 create mode 100644 test/PostInstall/readHSimple.cxx

diff --git a/test/PostInstall/CMakeLists.txt b/test/PostInstall/CMakeLists.txt
new file mode 100644
index 0000000000000..50a98b1ff5722
--- /dev/null
+++ b/test/PostInstall/CMakeLists.txt
@@ -0,0 +1,21 @@
+cmake_minimum_required(VERSION 3.20 FATAL_ERROR)
+
+project(PostInstall)
+
+find_package(ROOT REQUIRED)
+
+add_executable(readHSimple readHSimple.cxx)
+target_link_libraries(readHSimple PUBLIC ROOT::Hist ROOT::RIO)
+
+include(CTest)
+
+if(BUILD_TESTING)
+  add_test(NAME run-hsimple
+    COMMAND ${ROOT_BINDIR}/root.exe -b -q -l -e ".x ${CMAKE_SOURCE_DIR}/../../tutorials/hsimple.C" -e "return"
+    WORKING_DIRECTORY ${CMAKE_BINARY_DIR})
+  add_test(NAME read-hsimple
+    COMMAND $<TARGET_FILE:readHSimple>
+    WORKING_DIRECTORY ${CMAKE_BINARY_DIR})
+  set_tests_properties(run-hsimple   PROPERTIES FIXTURES_SETUP    HSIMPLE)
+  set_tests_properties(read-hsimple  PROPERTIES FIXTURES_REQUIRED HSIMPLE)
+endif()
diff --git a/test/PostInstall/readHSimple.cxx b/test/PostInstall/readHSimple.cxx
new file mode 100644
index 0000000000000..8ddb6e8ed8068
--- /dev/null
+++ b/test/PostInstall/readHSimple.cxx
@@ -0,0 +1,19 @@
+#include <TH1.h>
+#include <TFile.h>
+
+int main()
+{
+   TFile file("hsimple.root", "READ");
+   if (!file.IsOpen())
+      return 1;
+
+   TH1 *histo = file.Get<TH1>("hpx");
+   if (!histo)
+      return 2;
+
+   if (histo->GetEntries() != 25000)
+      return 3;
+   histo->Print();
+
+   return 0;
+}

From b960cd7681e869e5dc5d3644ac98dcd58d311d55 Mon Sep 17 00:00:00 2001
From: Stephan Hageboeck <stephan.hageboeck@cern.ch>
Date: Tue, 11 Mar 2025 16:35:55 +0100
Subject: [PATCH 2/2] [CI] Enable a small post-install CMake build test.

---
 .github/workflows/root-ci.yml | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/.github/workflows/root-ci.yml b/.github/workflows/root-ci.yml
index 41054f41444e7..5424b8cf5ef77 100644
--- a/.github/workflows/root-ci.yml
+++ b/.github/workflows/root-ci.yml
@@ -442,6 +442,11 @@ jobs:
         CONTAINER_IMAGE: "registry.cern.ch/root-ci/${{ matrix.image }}:buildready" #KEEP IN SYNC WITH ABOVE
         CONTAINER_OPTIONS: "--security-opt label=disable --rm ${{ matrix.property == 'gpu' && '--device nvidia.com/gpu=all' || '' }}" #KEEP IN SYNC WITH ABOVE
 
+    env:
+      BUILD_DIR: /github/home/ROOT-CI/build
+      INSTALL_DIR: /github/home/ROOT-CI/install
+      POST_INSTALL_DIR: /github/home/ROOT-CI/PostInstall
+
     steps:
       - name: Configure large ccache
         if: ${{ matrix.is_special }}
@@ -586,6 +591,18 @@ jobs:
         run: |
           ccache -s || true
 
+      - name: Install
+        run: "cmake --install ${{ env.BUILD_DIR }} --prefix ${{ env.INSTALL_DIR }}"
+
+      - name: Build post-install test project
+        run: |
+          cmake -S test/PostInstall/ -B ${{ env.POST_INSTALL_DIR }} -DCMAKE_PREFIX_PATH=${{ env.INSTALL_DIR }};
+          cmake --build ${{ env.POST_INSTALL_DIR }};
+
+      - name: CTest in post-install test project
+        working-directory: ${{ env.POST_INSTALL_DIR }}
+        run: ctest -j $(nproc)
+
   event_file:
     # For any event that is not a PR, the CI will always run. In PRs, the CI
     # can be skipped if the tag [skip-ci] or [skip ci] is written in the title.